Dust filter



H. J. HERSEY, JR

DUST FILTER July 3, 1951 Filed June 21, 1949 2 Sheets-Sheer. 1

/ ATTORNEY July 3, 1951 H. J. HERsEY, JR

DUST FILTER 2 Sheets-Sheet 2 Filed June 21, 1949 f f INENToR HJHERSE YJR.

l* ATTORNEY atentecl .ulzy 3,

UNITED STATES PATENT OFFICE DUST FILTER Henry J. Hersey, Jr., Chatham, N. J.

Application June 21, 1949, Serial No. 100,324

11 Claims.

l The present invention relates to dust filters of the type wherein dust-laden air or other gas is caused to flow through a porous filter medium as a result of a differential in gaseous pressure on opposite sides of the filter medium. The particles contained in the dust-laden gas accumulate on the high pressure side and, depending upon the nature of the equipment and of the particles contained in the dust, the porosity of the filter medium is gradually reduced and the filtering eiciency drops to such an extent that it is necessary to clean the filter medium. The present invention relates particularlyto a filter of the general type described, in which provision is madeV for cleaning the filter medium, without interruption of the operation of the filter, by means of a jet of air or other gas directed through the lter medium in a direction opposite to the fiow of the gas being filtered. This dislodges the accumulated particles from the high pressure side of the filter medium in a zone immediately adjacent this reversely directed jet. Preferably the jet of cleaning gas is supplied through a restricted orifice or nozzle carried by what may be called a blow-tube. Preferably means is provided for producing relative motion between the blow-tube and the filter medium so that the entire surface of the filter medium may be subjected to the cleaning operation.

The particles dislodged by the cleaning operation are projected into the incoming dust-laden gas and in the devices heretofore known, a certain portion of the particles will become suspended in that gas only to be redeposited upon the filter medium. To the extent that this occurs, the filtering operation is less efficient than it should be.

It is a particular object of the present invention to provide a filter of the general type described, having means for cleaning the filter medium by reverse jet operation in which substantially all of the particles dislodged in the cleaning operation are dislodged into a zone of the filter which is substantially free from the turbulence normally associated with the incoming dust-laden gas. This zone is so arranged with respect to the blow-tube that the particles dislodged by the blow-tube may gravitate to a position for ultimate disposal. In this manner there is very little tendency for any portion of the dislodged particles to redeposit upon the filter medium.

One of the features of the present invention is the provision of a receiver positioned on the high-pressure side of the filter medium and so arranged with regard to the cleaning nozzle or blow-'tube as` constantly to be disposed adjacent the area of the filter medium upon which the cleaning nozzle is working at any given moment. In general the receiver is so shaped as to correspond with the shape of the cleaning nozzle and to lie quite close to the high-pressure surface of the filter medium. It is so disposed that the material dislodged from the filter medium by the blast from the cleaning nozzle will be propelled into the receiver. The receiver, furthermore, is preferably so shaped that it will guide the particles and permit them to gravitate within the receiver to a hopper or similar accumulator at the bottom of the filtering device. The receiver, therefore, defines a zone which is relatively free of the normal movement of the dust-laden gas toward the filter medium and the tendency of the dust-laden gas to rush toward the freshly cleaned surface carrying the dislodged particles with it, will be very greatly reduced.

Another feature of the present invention is its provision for the use of fragile filter mediums which require a foraminous support or reinforcing structure on the low-pressure side to enable it to support the load of accumulated particles and to enable it to withstand the differential in gaseous pressure existing between the highpressure and low-pressure sides. For example, filter mediums such as very thin felt or paper or paper-like material may be reinforced by a screen or lattice work so that very large areas thereof may be exposed to dust-laden gas. The present invention provides a structure wherein enormous areas of fragile filter medium supported by suitable reinforcing structures may be used and subjected to a continuous and eiiective reverse jet cleaning operation. Heretofore reverse jet cleaning of efiicient type has been available only in connection with strong filter mediums. l

In the present invention the cleaning nozzle is made long and thin and is positioned between the reinforcing structure and the filter medium. The pressure of the dust-laden gas will cause 'the iilter material to press closely against the reinforcing structure and to bend around the cleaning nozzle, elongating the outer surface thereof. Appropriate mechanical means may be provided for causing relative movement between the filter medium and the cleaning nozzle while the latter remains between the reinforcing element and the filter medium.

It is an object of the present invention, there- 3 fore, to provide a filtering device of the type in which a porous and flexible filter medium in'the nature of felt, cloth, paper or the like may be used, and in which a very highly efficient cleaning operation is performed to greatly enhance the capacity of the lter.

It is a further object of the present invention to provide a filtering device in which very large areas of a fragile iilter medium may be supported by reinforcing means `and at the same time be so arranged as to be effectively cleaned to maintain a high capacity.

Other and further objects of the present invention will in part be obvious and will in part become apparent from a consideration of the following detailed description of apreferred, but not necessarily the only, form vof the invention taken in connection with the drawings accompanying and forming a part of this specification.

In the drawings: Fig. 1 is a vertical sectional view of a dust filter embodying the present invention, with certain parts thereof not in section for the purpose of clarity of illustration;

Fig. 2 is a top plan view of the apparatus shown lin Fig. 1;

the receiver;

Fig. 4 is a fragmentary horizontal section taken along the line 4-4 of Fig. 1 and showing the relation of the cleaning nozzle, the receiver and the reinforcing structure for the filter medium; I Fig. 5 is a -vertical sectional view showing the details of -vthe coupling through which cleaning air is conducted to the nozzle-supporting structure; and

Fig. 6 is an elevational View of the cleaning nozzle.

Referring now to thedrawings, a dust filter embodying the features of the k present invention is shown as .comprising a generally cylindrical body IIJ defining a chamber having a tapered w,lower section I2 which communicates with a hopper (not shown) for receiving the particles which have been separated from a gas lin the operation of the Vfilter. The filter mechanism is enclosed within the cylindrical body I and comprises a tube I4 made of any suitable porous .filter medium. Preferably the material from which filter I4 is made is a felted material such as -felt or paper, although certain of the features .of the present invention will be found to Ibe of value when used in connection with filtering lmediums of variousv materials. The tubular lter medium I4 is so mounted in the chamber Ill, I2 as to define a sub-chamber of generally cylindrical conformation.

For purposes of illustration of the present invention, it may be assumed that the filter medium I4 is made of felt and is sufliciently fragile to need the support of some form of perforated reinforcing means. Thus there is shown a reinforcing frame I 6 which may be made of wire screen of a mesh-size suitable for the particular filter medium used. From a consideration of Figs. 1 and 4 it will vbe observed that the vfilter medium I4 is of greater diameter in .any

given horizontal .plane than the reinforcing frame I6. The difference in diameter is just Vsufcient to permit the positioning between the T reinforcing frame and the filter Vmedium I4 vof .an elongated cleaning nozzle or blow-tube I8 provided with an elongated orifice Y20 positioned in the apex of a triangular front wall 22 of the blow-tube I8. The shape of the front wall 22 of the blow-tube I8 is such that the filter me dium may be smoothly curved when pressed thereagainst `by the gaseous pressure on the high-pressure side. The portion of the filter medium immediately opposite the orifice 2li at any given time will be rather sharply bent as indicated in Fig. 4. The elongation of the outer surface of the filter medium serves to open the interstices thereof and to facilitate the dislodgment of the accumulated particles as will be more fully explained hereinbelow.

The dust-laden gas or air is introduced to `the lter through an inlet 24 which preferably .is connected with the cylindrical body I@ at the upper end thereof in such manner that the gas will enter -tangentially and circulate around and .downwardly of the interior of the chamber outside the filter medium. The dust-laden gas may be `supplied under pressure or may be drawn through the filter by fans on the discharge side. -In either event, the interior surface of the filter medium is under a lower pressure than the exterior thereof and thegas which carries the dust `will flow through the filter medium, leaving the particles deposited on the high-pressure surface thereof. The cleaned gas will ilow into the subchamber defined by the filter medium and upwardlyto .an outlet 26.

As Ashown in Fig. 1, the filter medium I4 is supported at the top upon an annular ring 2,8 carried by the body I-Il. Desirably the annular ring 28 vis formed-witha lbead 30 over which the upper edge of the .tubular filtering medium I4 vmay be bent outwardly vand downwardly. The upper edge "of the filter medium may be secured -to the ring'28 bya .band '32 which maybe made of contractile material or may be provided with a turnbuckle or other suitable device whereby it may be contracted upon such upper edge.

It -will be observed that the reinforcing frame I6 andthe filter medium I4 `are generally cylindrical in shape and that the blow-tube I8 and slot 2li coincide generally with an elementiof the cylinder. A self-supporting filter `medium `could rbe truly cylindrical or have any other generally V`I-I are -frustoconical with `the lower ends of somewhat smaller diameter than the upper .ends thereof. This provides for accurate adjustment kof the tubular filter medium I4 .in telescopic relation upon the reinforcing frame to leave just enough slack for movement of the .blow-.tube I8 therebetween. Obviously, the iilter medium I4 should not beso slack upon the .reinforcing frame that wrinkles `or pleats may occur rbecause wrinkled or pleated areas will not be effective for filtering purposes. Similarly, the `relationship should not ybe so tight that undue friction is set up between Ythe filter medium and the blow-tube I8 d uring the course `*of movement of the blowtube around the central axis of the filter.

The filter medium I4 v.may be made of the desired shape by cutting lthe -material from `a flat sheet and tapering C,o negor n.both of the ends and Vjoining theseends in.any suitable manner as `by vvc lesired extentand the .upper edge maybe secured r`'0 0 the annular @e128 Eas apoye described.

At its lower end the body of filter medium I4 is attached to a disc 34 which is provided with a lip 36 and a band 38 which operate in the same manner as the lip 36 and band 32 just described. The disc 34 is imperforate except at its center where it receives a vertically disposed hollow shaft 40. The shaft 40 is received in a bearing 42 in the disc 34.

A flexible boot 44 is provided for sealing the bearing and the lower end of the hollow shaft 40. The boot 44 is made of rubber or rubberized fabric and is generally conical in shape. A sharply tapering helical spring 45 is positioned within the boot. The narrow end of the boot 44 is clamped to the exterior of the shaft 40 by a conventional clamping ring 48. A flange 46 is secured to the wide end of the boot 44 and is pressed into contact with the disc 34 by the expansive action of the enclosed spring 45. When the lter is in operation the pressure of the dust-laden air will be effective to press the flange 46 more tightly against the disc 34. In this manner the dustladen air in the chamber exterior of the lter medium is excluded from entering the sub-chamber interior thereof through the bearing 42. Inasmuch as the entire lower end of the lter medium I4 is tightly closed by the disc and the sealed bearing therein, the clean gas which passes through the lter medium must flow upwardly for discharge through the outlet 26 as heretofore described.

At its upper end the filter is closed by a cover plate 50 which may be held down by a plurality of nuts 52 threadably received upon studs 54 secured to an inwardly-turned flange 56 of the body I of the filter. The cover plate as shown in Fig. l rests upon the portion of the filter medium turned over the annular ring 28 and thus effectively seals the filter.

The cover plate 58 is provided with a suitable opening for communication with the outlet 26. The outlet 26 may comprise an elbow secured to the cover plate by a flange 58, if so desired.

Cover plate D is also provided with an opening for receiving an elongated sleeve-like bearing 68 which surrounds the hollow shaft 40. The bearing 68 is supported by an overhead framework which desirably may be formed from a horizontally extending channel 62 having extensions 64 at the opposite ends thereof in such position as to be secured to the body I6 of the filter by cap screws 66 or the like. The overhead frame just described serves to support the driving mechanism and other accessory equipment for the operation of the filter, as will be more fully described hereinbelow.

The hollow shaft 48 is provided with a suitable thrust bearing 68 which rests upon the overhead frame member 62. The bearing 68 and the elongated bearing 68 therefore provide adequate support for the hollow shaft 40 in vertical and horizontal directions. The construction just described is desirable inasmuch as the lower end of the hollow shaft 40 is free.

The foraminous support or reinforcing frame 4I6 is supported by the hollow shaft 40 through 6 to hubs 13 which rest upon the set screw collars 'i0 and which are freely rotatable with relation to the shaft 40.

Since the lter medium I4 is secured to the outer body I6 of the lter, it will serve to hold the reinforcing frame I6 against rotation with the -hollow shaft 40.

The overhead frame member 62 has secured thereto a base plate 80 upon which is mounted a suitable motor M, a speed reducer 82, and a blower 84. The blower 84 preferably is of the rotary positive pressure type while the speed reducer 82 may be of any suitable type capable of imparting rotation to the shaft 40 at a speed of a few revolutions per minute.

As shown in the drawings, the shaft 86 of Amotor M carries two pulleys. A pulley 88 is connected by a belt 90 to a pulley 92 on the shaft ,94 of the blower 84. A pulley 96 on the motor shaft is connected by a belt 98 to a pulley |00 on the shaft |62 of the speed reducer 82.

The speed reducer 82 may drive the hollow shaft 48 through a gear |04 and a gear |86 fixed to the hollow shaft 40.

The air intake of the rotary blower 84 is indicated at |05 and it is preferably tted with an air cleaner IIi'I. The air outlet of the blower 84 is indicated at |68, A flexible coupling ||0 such as a rubber hose is connected between the outlet |88 and an inlet ||2 (Fig. 5) formed in a hollow hub I I4 surrounding the hollow shaft 4D. rIhe hub |14 has a recess ||6 therein which is in communication with the inlet I I2, and the hollow shaft 48 may be provided with a plurality of openings IIS communicating with the recess ||6 whereby air supplied under pressure from the `blower 84 is admitted to the interior of the hollow shaft 46. The hollow shaft 4i) is made airtight at the top and bottom by the use of suitable plugs or caps.

The hollow shaft 40 has secured thereto a tubular arm |26, the interior of which is in communication with the interior of the shaft 40. At its outer end the arm |26 is provided with a set screw |22 for adjustably securing an inlet tube |24 in closely-fitting telescopic relation with the tubular arm |28 for a purpose to be described. Toward its lower end the hollow shaft 46 is provided with a second tubular arm |26 the interior of which is in communication with the interior of the hollow shaft 40. At its outer end the arm |26 carries a set screw |28 for adjustably securing a hollow inlet tube |36 in closely fitting telescopic relation with the arm |26 for a purpose to be described.

Referring now to Figs. 5 and 6, it will be observed that the tubes |24 and |36 are located at the upper and lower ends, respectively, of the blow-tube I8. They are in communication with the interior of the blow-tube whereby air supplied under pressure by the blower 84 is conducted to the blow-tube at both its upper and lower ends. This insures an adequate supply of air for discharge through the orifice 20.

As described above, the blow-tube I8 lies between the reinforcing frame I6 and the lter medium I4. Rotation of the hollow shaft 40 is imparted through the tubular arms |28 and |26 to the blow-tube whereby the blow-tube is progressively moved around the filter for cleaning of the entire surface thereof. Dependingupon the nature of the particular lter medium in use and upon the closeness of t of the tubular body of the lter medium I4 upon the reinforcing frame E6, the exact positioning of the blow-tube "1I-lli may 'have 'to be adjusted. The set screws |22 and V'W8-are provided so that such adjustment may be made rapidly and conveniently.

' yAt its zlower end and beyond the bottom disc '34 the hollow shaft 4G carries a'general-ly semicircular frame |32. The frame |32 is secured to the shaft 40 through a hub |34 and set screws |36; The frame |32 ycomprises a cross member I38'secured to the hub |34 and to spaced arms |45 also secured to the hub |34.

VAt their outer `ends the arms |40 carry a Vertically disposed channelshaped receiver |42 having inwardly directed flanges |44 which are spaced from one another a distance about equal to and preferably greater than t-he width of the 'blow-tube I8. rIhe flanges |44 extend toward the filter medium almost into contact therewith along vertical Alines Vdisposed on either side of the blow-tube. This-"relationship is clearly shown in Fig. 4, for example. When the iilter medium I4 and reinforcing frame 'i6 are tapered as shown in the drawing, the receiver |142 is tapered in-such vmanner that the anges y|44 become progressively shorter toward the upper'end of the receiver and thus conform to the shape of the lter medium.

At its upper end the receptacle |42 is provided with a horizontally disposed inwardly turned ila-nge |46 which serves substantially to close the upper end of the receptacle by extending inwardly almost into contact with the surface of the filter medium i4 in the position to which it is displaced by the blow-tube I8. At its lower end the receptacle |42 is open so that the solids dislodged from the surface of the filter medium I4 by the blow-tube |8 may gravitate directly to the lower portion I2 of the filter for accumulation with such solids as may fall from the outer chamber and from the remainder of the surface of the lter medium in the normal course of operation.

For purposes of stability the receptacle |42 may be braced by means of angularly-disposed curved braces |48 which extend from the opposite ends of the cross arm |38 exteriorly of the filter medium I4. The braces |48 may be secured at suitable points along the length of the receptacle |42 as by cap screws |59.

The construction irst described provides for simultaneous movement of the blow-tube I8 and receiver |42 relative to the filter medium I4 whereby the solids dislodgedv from the filter medium by the blow-tube I8 will always be propelled into the receiver. The walls |44 and top flange |46 serve substantially to isolate the interior of the receiver from the currents of dustladen gas circulating within the chamber dened by body lil and therefore the solids are left almost entirely free of any tendency to re-deposit upon the freshly cleaned portion of the filter medium |13. The solids are discharged by gravity from the lower end of the receiver |42 into a zone which is almost entirely free of currents which might tend to carry them upwardly toward the filter medium. Thus the present invention provides a iilter in which a very large portion of the solids dislodged by cleaning are directly conducted to the accumulating zone or hopper and in which there is no secondary problem of gas and solids separation such as is presented by all of the reverse jet cleaning devices of the prior art with which I am familiar.

The principles of the present invention are clearly adaptable'to dust filters of differing specific structure. For example, the positioning of the inta-hehehe of the ilterwellabove the Zoiiejw'ithin which the receiver Adischarges the 'solids'dish lodged -by-revers'e jetcleaning -apparatus presents' Athe very lgrea-t-advaritage that lthe dislodgedsolids do not become mixed with the incoming 'dustila-den gas'irrespective -of the particular lshape "or typeof lter medium or blow-tube used.

Similarly, the positioning of the blow=tube `be- Jtv'veen't-he'lter medium and the iorarninous support A'i'fherefor makes it possible `to achieve'the `benefits -of reverse jet Ycleaning in which "the blow-tube isinsdirect'contact'with the filter me `dium vand in 'which' the filter medium is'bent around the blowetu'be to lopen the interstices Ithereof in conjunction with fragile filter Ymee' diums of any shape or type with which aforain; inous 'support must be used. l

In the preferred form of filter chosen for "illustration, the filter 'medium I4 defines 'a subchaiiiberinto which the cleaned gas'ilows fordis'- charge through the outlet 26. In certain fo'rin's o'f filters'towhich portions, at least, ofthe present invention may be 'adapted where the dust-'laden gas kis supplied under superlatmo'spheric pres-V suregthecleaned vgas may be 'allowed to escape directly vfrom the surface of the filter medium to `the atmosphere. In such event the side ofthe V'iilter medium exposed to the atmosphere willbe the low pressure side and the blow-tube `I8 will be located on that side whether that side beth'e vinterior or exterior side of a generally cylindrical filter medium or merely one side of a lterinediu'm of flat or other'shape.

The' VKdetailed description herein given 'of a `preferred form of 'myinvention is to be taken iii 'an illustrative Yrather than in a limiting Vsensearid theI scope of the invention is'to be limited only by the appended claims.

What is claimed is:

1. A dust filter comprising a chamber having generally vertically disposed Walls and a portion near the `bottom thereof for vcollecting dust particles which gravitate to said portion, a porous filter medium 'suspended within said chain-ber and liori'nirig' a generally vertically disposed wall defining av subchamber communicating with' said chamber only through said porous filter medium, means for directing dust-laden gasto said chard- `ber under Vgaseous pressure greater than that existing in' said subchamber to cause said gas 'to pass through said filter medium and to deposit a la'yerof 'the solids forming said dust on thehigh pressure surface of said filter medium, means for cleaning said filter medium comprising a .hllow member having Va wall engaging the low pressure side of said filter medium and having an ori'iice formed in said wall, means for supplying air ata gaseous pressure'substantially higher than that existing in said chamber for discharge through said orifice and through said filter medium to dislodge a portion of said layer of solids in a .zone oi'apo'site saidV orifice, and a receiver located within said chamber in close proximity with .that por;

tion of the high pressure side of said filter medium from which said solids are dislodged, said receiver being open at the bottom whereby the particles dislodged from said filter medium and propelledy into said receiver m-ay gravitate within said receiver for discharge from the bottom thereof into the dustcollecting portion of said chamber.

.2. Adus't lter comprising a chamber having generally vertically disposed walls and a portion near thebo'ttoni thereof for collecting dust particles which gravitate to said portion, a porous filter medium suspended within said chamber and forming a generally vertically disposed wall defining a sub-chamber communicating with said chamber only through said porous filter medium, means for directing dust-laden gas to said chamber under gaseous pressure greater than that existing in said sub-chamber to cause said gas to pass through said filter medium and to deposit a layer of the solids forming said dust on the high pressure surface of said filter medium, means for cleaning said filter medium comprising a hollow member having a wall engaging the low pressure side of said filter medium and hav ing an orifice formed in said wall, means for moving said hollow member over the surface of said filter medium, means for supplying air at a gaseous pressure substantially higher than that existing in said chamber for discharge through said orifice and through said filter medium to dislodge a portion of said layer of solids in a zone opposite said orifice, and a receiver located within said chamber in close proximity with that portion of the high pressure side of said filter medium from which said solids are dislodged, said receiver being open at the bottom whereby the particles dislodged from said filter medium and propelled into said receiver may gravitate within said receiver for discharge from the bottom thereof into the dust-collecting portion of said chamber.

3. A dust filter comprising a chamber having generally vertically disposed walls and a portion near the bottom thereof for collecting dust particles which gravitate to said portion, a porous lter medium suspended within said chamber and forming a generally vertically disposed wall defining a sub-chamber communicating with-said chamber only through said porous filter medium, means for directing dust-laden gas to said chamber under gaseous pressure greater than that existing in said sub-chamber to cause said gas to pass through said filter medium and to deposit a layer of the solids forming said dust on the high pressure surface of said filter medium, means for cleaning said filter medium comprising a hollow member having a wall engaging the low pressure side of said filter medium and having an orifice formed in said wall, means for moving said hollow member over the surface of said filter medium, means for supplying air at a gaseous pressure substantially higher than that existing in said chamber for discharge through said orifice and through said lter medium to dislodge a portion of said layer of solids in a zone opposite said orifice, and a receiver mounted in said chamber for movement with said hollow member in close proximity with the high pressure surface of said lter medium, said receiver having an opening generally coextensive with and positioned directly opposite the orifice in said hollow member for receiving the solids dislodged froni said filter medium, and said receiver having an opening from which said solids may gravitate into the dust collecting portion of said chamber.

4;. A dust filter comprising a chamber having generally vertically disposed walls and a portion near the bottom thereof for collecting dust particles which gravitate to said portion, a porous filter medium suspended within said chamber and forming a generally vertically disposed substantially cylindrical wall defining a sub-chamber communicating with said chamber only through said porous filter medium, means for directing dust-laden gas to said chamber under` gaseous pressure greater than that existing in said sub-- chamber to cause said gas to pass through said filter medium and to deposit a layer of the solids forming said dust on the high pressure surface. of said filter medium, means for cleaning said iilter medium comprising a hollow member having a wall engaging the low pressure side of said filter medium and having an orifice formed in said wall, means for moving said hollow mem-v ber over the surface of said filter medium, means for supplying air at a gaseous pressure substantially higher than that existing in said chamber for discharge through said orifice and through said ltermedium to dislodge a por` tion of said layer of solids in a Zone opposite; said orifice, and a receiver mounted in said chamber for movement with said hollow member in close proximity with the high pressure surface of said filter medium, said receiver having an opening generally coextensive with and posi-` tioned directly opposite the orifice in said hollow member for receiving the solids dislodged from said filter medium, and said receiver having an opening from which said solids may gravitateA into the dust collecting portion of said chamber.

5. In a filter for separating particles of'solid material from a gas in which said particles are: suspended, a flexible filter medium previous to gas and impervious to at least a portion of ther solids suspended in said gas, means for supporting, said filter mediumand .holding it inl generally cylindrical shape, means for directing said gas and the particles suspended therein to one surf. face of said filter medium under gaseous presi-i sure greater than that on the other surface of said lter medium to cause said gas to. pass;n through said filter medium` and to deposit a layer of said solids on the high-pressure surface thereof, a blow-tube, means for supporting said blow` tube in contact with the low pressure side of said filter medium, said blow-tube having a slotA extending lengthwise thereof and openinginto. Contact with said filter mediumV along a line. substantially coinciding with an element of the generally cylindrical body of said filter medium, the, gaseous pressure on the high pressure side of said filter medium being effective to press said lter medium into contact with said blow-tube and to cause a bending of said filter medium: around said blow-tube elongating the high prese,

sure surface thereof, means for supplying gas.,

under pressure to said blow-tube forv discharge through said slot and through said filter mediumin the zone of elongation to dislodge a portion. of said layer of solids in a zone opposite said slotymeans for rotating said blow-tube around. the axis of the generally` cylindrical body of.saidl filter medium to bring said tube and the slotk therein progressively into contact with substantlyrv the entire low pressure surface of said filter me-E dium for cleaning substantially the entire high pressure surface thereof.

6. In a dust `filter the combination of a poro Iiexible filter medium; means on one side of. said iilter medium for receiving a fiow of dust-v laden gas at a gaseous pressure greater than that existing on the opposite side of said filter medium whereby the gas may pass through said filter.l

medium and the solid particles of said Adust will be detained by said filter medium; a foraminous, relatively rigid support substantially co-extensive. in area lwith said filter medium and supported, adjacent said filter .medium on the low pressure side thereof; and means for cleaning said. filter 4 medium includinga blow-tube having an orifice Il therein, means for' supporting said blow-muera aposition between said filter" mediumfand said foraminous support v,with the orifice thereof in cfiitacty with the'surface of said lter-'Ifiedium on the lo'w`pres`sur`e side, means for supplying air to said blow-tube at apressure substantially greater than that existing ori the'y high pressure side of said filter medium for discharge through said orifice and through said lter medium, and means for 'causing relative movement between said blowtube'ardsaid filter rediuih for progressive cleani'gl of a. substantial area of said filter medium.

7. Ina dust filter', thev combination of a forami-v nous relatively rigid support, a porous flexible filter Inediuni nun'ted adjacent said support one surface thereof adapted to rest against said support, means on the side of said filter oppsite Ysaid support for receiving a how' of dusteladen gas at a gaseous pressure greater than that existingv` on thev other side of said lter rnediunwliereby saidV filter medium will be pressed against said forar'ninous support and the' gas may pass through said lter medium and the solidn particles of said dust will be' retained by said fiii'r medium, a blow-tube having an orifice therein, said blow-tube being supported between said fora'ninous supprt and said filter n 'i'ediurnY in such' position that the orifice of said blow-tube is disposed for Contact with the low pressire side of said filter medium, the gaseous lfeSSvre f Said dust-lade gas being electve t fess the piti f said filter Idulfi displaced frioi'riisaid su'pprtby said blow-'tube into contact withk said blow-tube and thereby to cause a be'dingof said Ylter nedium around said blow'- tiibe elongating the high pressure surface Vthereof, means'A fof supplying' ai-rt said blow-tube at a'y ,ressure substantially greater than that existiijig on the high pressure sidev of said filter inefor dischargeV through' said orifice and said filter medium irri the zone of elongation, and I'neans forcausin'g relative movement between said blow-tube and said filter `nedium for progiressive cleaning' of a substantial area of said iter rediu'in. Y Y

l 8,. In a dust lter the; combination of arforaminous relatively rigid support of generally cylindrical conformation, a porous flexible filter rnedium of generally `cylindrical conformation unted' in telescoping relation withl said supprtv with one surface thereof adapted to restv against said support, meansV on the side of said filter medium opposite said support for receiving a` flow of dust-laden gas at a' gaseous pressure greater than that existing on .the other side of said filter' medium whereby said filter medium will b e pressed against'said foraminous support andthe gasI may' pass through said filter medium andthe solidparticles of said dust will be retained by said filter medium, a blow-tube having' an elongated slot'alikeorifice therein, said blow-tube being supported between said foramisupport and said filter mediuni such positiori' that the o r'i ce in said blow-tube is disp'osedhfor contact 'withthe lowv pressure side of 'fa `inter medium in substantial eoincidenc'e'with Y eriientof the generally cylindrical bodyy of ,i A, filter medium, th'egaseouspressure of said djist-'lagien gasV being effective to press the port'iljof said filter medium displaced from said support by said blow-tube and thereby cause 'a beding of said lte'r inediumnaroundmsaid Yblowe'elongating the high pressure surface thereoffni'nearis for supplying air to said blowetube at a pressure substantially greater' thah'tha-t eXist` 112 ing' on the' high pressure sidev of said filter meidium for discharge throughv said orifice and saidfilter medium in the Zone of elongation, ahdmeans for causing relative movementk between said blow tube and said filter medium for pro'- gressive'cleaning of ay substantial area of Said4 filter medium.

9. In a dust filter the combination of a porous' llexible filter medium of generally cylindrical conformation; means on the outside of said lter' medium for receiving a flo'w ofdust-lad'ei'i gas at a gaseous pressure greater thanA that existing on the inside of said filterv medium whereby the gas' may pass through said filter medium and the solid particles of said dust will'be detained by' means for supplying air to said blow-tube' atV a pressure substantially greater than thatA existing' on the' high pressure sid'of said lter medium' for discharge through said orifice and throughV said filter medium, and means for lcausingl relative movement between said blow tube and said lter medium' for progressive cleaning of a substantial area of said' filter medium.

1'0. In a dust ltei' the combination of a porous flexible lter medium of tapering cylindrical conformation; means'on the outside of said filter iiiediiim for'recei'vir'igV a flow of dust-laden gas at a gaseous pressure greater than that existing on" the inside' of said filter medium whereby the gas may pass through said filter rr'iediui'n and' the solid particles of said dust will bev detained by said filter medium; a forani'inous, relatively rigid support of tapering cylindrical conformation corresponding with the conformation of said filter medium and supported within said filter medium; means for cleaning said filter medium including a blow-tube having an orifice therein, means for supporting saidblow-tube in a position between said filter medium and said fora'm'inous support with the orifice thereof in contact with the surface of said filter medium on the low pressure side, means for supplying air to said blow-tube at a pressure substantially greater than that existing on the high pressure sideof said filter medium Yfor emission from said orifice, and means for causing relative movement be'- tween said blow-tube and said filter medium for" progressive cleaning of a substantial area of said filter medium; and means affording lengthwise adjustment of said filter medium uponV said fora'niinous support to Vary the closenessl of fit of said filter rn'ediuin upon said support and blow tube.

11. A dust lter comprising a chamber having generally vertically disposed walls and a portion near the bottom thereof for collecting dustv partlcles which gravitate to said portion; a foraminous relatively rigid support; a porous flexible filter medium suspended within said chamber adjacent said support with one surface thereof adapted to rest against said support and the other surface thereof facing said chamber, said filter medium and said support defining a subchamber communicating with said chamber only through said porous filter medium and said foraminous support, means for directing ldi'istladen gas to said chamber under gaseous pressure greater than that existing in said sub-chamber whereby said lter medium will be pressed against said foraminous support and the gas may pass through said filter medium and the solid particles of said dust will be retained by said lter medium in the form of a layer of solids on the high pressure surface thereof; and means for cleaning said lter medium comprising a hollow member having an oriiice,v said hollow member being supported between said foraminous support and said filter mediumin such position that the orifice in said hollow member is disposed for contact with the low pressure side of said lter medium, the gaseous pressure of said dust-laden gas being effective to press the portion of said lter medium displaced from said support by said hollow member into contact with said hollow member and thereby tofcause a bending of said iilter medium around said hollow member, means for moving said hollow member over the surface f said filter medium, means for supplying air at a gaseous pressure substantially higher than that existing in said chamber for discharge through said oriiice and through said filter medium to dislodge a por- 2 tion of said layer of solids in a zone opposite said orifice, and a receiver mounted in said chamber for movement with said hollow member in close proximity with the high pressure surface of said lter medium, said receiver having an opening generally co-eXtensive with and positioned drectly opposite the oriiice in said hollow member for receiving the solids dislodged from said filter medium, and said receiver having an opening from which said solids may gravitate into the dust-collecting portion of said chamber.

HENRY J. HERSEY, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 996,860 Kastner July 4, 1911 1,498,061 Adams June 17, 1924 1,995,648 Rathbun Mar. 26, 1935 2,364,877 Smellie Dec. 12, 1944 2,474,478 Hart June 28, 1949 FOREIGN PATENTS Number Country Date 16,392 Great Britain May 30, 1912 554,893 Germany July 15, 1932 

